Power hammer



July 10, 1923.

R. C. SCHROTH. JR. ET AL POWER HAMMER Filed June 10 1920 grwentom rallz/J.

Ebb: Li fib 21 m an I (5 WWW? Patented July 10,. 1923.

UNITED s'r'r'us PATENT o-FFlcE. I 1

ROBERT C. SCHROTH, JR.,'OF NEW YORK, N. Y., AND CLAUDE A. HERMAN, BRIDGE PORT, CONNECTICUT. H

POWER HAMMER.

Application filed June 10, 1920. Serial No. 387,839.

To all whom it may concern.

Be it known that we, ROBERT C. SoHRorn, J r., a citizen of the United States,.and resident of New York City, inthe county of New York and State of New York, and CLAUDE A. HERMAN, a citizen of the United States, and resident of-Bridgeport, 'in the county of Fairfield and State of Connecticut, have invented certain new and useful Im- 10 provements in Power Hammers, of which the following is a specification. This invention relatesto new and useful improvements in power hammers wherein the power'is conveyed'through the medium of a rotating flexible shaft to a reciprocat ing plunger. and from the reciprocating. plunger or piston to the. impact tool through an air cushion. The object of this invention is to provlde a construction as outlined in which the v1- bration and jar isv entirely eliminated in so far asthe operator is concerned through the arrangement of an air cushion between the power and the tool. c

Other objects reside in the particular construction and arrangement of parts hereinafter more specifically described and claimed.

. Reference will be had to the accompanying drawings forminga part of this specification and wherein like reference characters designate corresponding parts throughout the several views, in which Fig. 1 is a transverse vertical sectional view and Fig. 2 is a longitudinal tional view.

In the drawing the casing is represented by the character A and is cylindrical 1n 40 form, being provided with the internal sleeve B to form a suitable lining for the moving parts. It will be seen that an annular shoulder is formed in the lower end of the casing A for the reception of the external annular flange 2) formed on the lower end of the sleeve B. The upper end of the casing A is provided with crank casing A,

transverse secan inwardly projecting annular shoulder c.

that engages and guides the tool D. Within this cap C is positioned'the cushion member c'and a guide block d, the latter being, seated against an annular shoulder of the cap and projecting into the internal sleeve or cylinder B. The-shankof the tool D is supported in the aligned central hole's of these guide members 0 and-03, the shoulder of the tool being positioned against the cushion member 0 while the freerend ex-' tends through the block. d to contact with the reciprocating free piston The cush-I ion member cis loosely mounted in .thecap' C and upon theshank of the tool D and is Q normally held against the shoulder of the, tool by meansof the springs c to better take up the recoil of the stroke of the tool. Conventional ports R through the casing A and sleeve B are for an obvious purpose.

This free piston E is operated by the movement of the piston F, which latter is connected throu h the piston rod 7 with the 1 crank shaft f. Tor driving the crank shaft 7 any suitable source of power maybe provided and the power transmitted therefrom by means of the shaft G, the end of which' is enclosed in'the casing 9. The endofthis drive shaft is connected to the crank shaft by any suitable means and in the present instance the end of the crankshaft denoted by f is formed with a socket in which the end of the drive shaft is seatedby means of the screw'shown.

.It will be seen that at there is an en- 9 larged offset portion of the casing having longitudinal bore H in which is arranged the slide valve J connected to' the trigger K arranged'in the handle and heretofore'men tionedi The link jwhich connects the slide I I valve J and the trigger Kis arranged for longitudinal movement'so that pressure on the trigger K will cause a forward movement of the slide valve against the tension of the sprin Z. The spring Z is seated in the lower enc of the bore and contacts with the lower end of the valve and the. adjustable screw Z which latter terminates the bore H.

The slide valve J includes a port 22 which at times serves to complete the passage from the interior of the casing to the atmosphere through the ports P, M and N. When this valve is shoved forward to close port 0 an airtight chamber is formed'in the casing be-- tween the adjacent ends of the two pistons E and If to provide an air cushion in said casing for a'purpose more clearly hereinafter explained. The passage M terminates in theannul'arpassa'geP and the latter communicates with the interior through a series.

of perforations formed in the inner sleeve or lining B. At P suitable oil ducts-may be provided for the lubrication of the moving parts.

Referring more particularly to the operation it willbe seen that through the driving shaft G movement of the crank shaft 7" and: reciprocating piston F is secured; As

1 long as the communication M is open to the atmosphere thereciprocation oj-f the piston F will have no effect upon the free piston E. When, however, this communication is closed through-. the operation of the trigger K and the valve J the free piston, E will receive the cushioned blow of'the piston F upon its top end, which drives the other end against the shank, of the tool D. Because of the air cushion, formed in the chamber, be-

tween the two pistons; all vibration. or jar caused by the impact isentirely eliminated.

\Vhenitisdesired,tostop the operation the.

trigger is released and the-spring actuated valve willreturn'to its normal open position to open the ports M, N. and; O7 to form a free passage from the cushion chamber'to the atmosphere. It will. also be apparent that the force of the blow, can readily be controlled by simple adjustment. of the valve and, its-trigger which; in turn regulates the flow. of'air to. or chamber.

It will, be quite obvious. that numerous changes may be made in thed'etailsof con struction without varying from the spirit of, the invention.

What we claim. as. new and, useful and,

desireto secure by Letters Patent, is

1. A power hammer comprising a, crank, a

cylinder enclosing said crank" andprovided with, an air passage communicating with;

the. interior through its wall,sa;id, cylinder further provided with an enlargech offset portion having a longitudinalbore, a posi-. tively drivenpiston'for compressing and ex:

panding the air ifn'saidcylinder, I a free piston adapted to-be operated-by the compresfrom the cushion 2. A power hammer including a cylinder having an air port and an enlarged oifset portion having a longitudinal bore, a positively driven piston, a tool, a cushioning member for the tool, a free piston arranged between said positively driven piston and said tool, a slide valve in said longitudinal bore for closing said port whereby 'an'air tight chamber is formed between the adjacent ends of the two pistons for the hperation of said free piston, and means for operating said valve, said means including a trigger adapted tov enter said longitudinal bore to move said valve against the action of a spring, V 1

3. A power hammer comprising a crank, a

cylinder enclosing said crank and provided with a chamber having a port, saidcylin der further provided with, a handleportion, a positively driven piston in said chamber, a

free piston, therein and adapted to actuate a tool, and means for forming an air cushion between said pistons or for destroying said air CHSlllOIl, said means includinga slide valve arranged in an offset portion Ofsaid cylinder and having a port communicating with the atmosphere and adapted to com; municate with the port of said chamber, a-

spring for normally holding said ports in.

register whereby atmospheric air may enter said chamber, and a trigger adapted" to cause the port of said chamber to be closed, said,

trigger arranged in said handle portiont.

Signed at Bridgeport in the county of Fairfield and, State, of, Connecticut this 9 tli day of June','A. D. 1920.

RQBERT (1,; SCHROTH, R. CLAU E A. Witnesses:

G. MMNEWMAN, L t ler: 

